Chapter 54: Community Ecology
Chapter 54: Community Ecology BYS 120
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This 0 page Class Notes was uploaded by Amelia Notetaker on Tuesday December 8, 2015. The Class Notes belongs to BYS 120 at University of Alabama - Huntsville taught by Dr. Luciano Matzkin in Fall 2015. Since its upload, it has received 14 views. For similar materials see Organismal Biology in Biological Sciences at University of Alabama - Huntsville.
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Date Created: 12/08/15
Chapter 54 Lecture Notes Communityinteractions 0 Community is a set of interacting species living in same environment 0 Types of interspeci c interactions 0 Competition Predation Herbivory Parasitism Mutualism Communalism facilitation o Niche 0 Total of a species use of biotic and abiotic resources ecological niche o Ecologically similar species can coexist in a community if there are one or more signi cant differences in their niches o Fundamental niches potentiay occupied by that species 0 Realized niche actuay occupied by that species 0 Competition 0 Interspeci c occurs when species compete for a resource in short suppe Competitive exclusion 0 Strong competition can lead to this Elimination of competing species 0 Resource partitioning 0 Outcome of competition could be this 0 The difference of ecological niches enabling similar species to coexist in community 0 Character displacement via competition 0 Tendency for characteristics to be more divergent in sympatric populations than in allopatric populations Predation Refers to interaction where 1 species the predator kills and eats the other prey Some feeding adaptations of predators are claws teeth fangs stinger and more Consequences of predation O Behavioral defenses include hiding eeing herd or school forming self defense and alarm calls Cryptic coloration blending in Aposematic coloration chemical defense exhibited with bright warning color 0 Some species mimic the appearance of others to gain protection Mimicry O O Miillerian mimicry 2 or more unpalatable species resemble each other batesian mimicry palatable or harmless species mimic an uneatable or harmful model Herbivory o Refers to an interaction which herbivore eats parts of a plant or alga Plants mechanical and chemical defenses and adaptations evolve to reduce herbivory Parasitism 0 One organism parasite derives nourishment from another organism host which is harmful in the process 0 Endoparasites live within body of their host 0 Ectoparasites live on external surface of host 0 Can have multiple hosts Mutualism 0 Positive interaction the bene ts both species Obligate 1 species can39t live without the other Faculative both species can live alone Commensalism 0 One species bene ts and the other is neither harmed nor helped Species diversity of communities 0 Species diversity of a community is the variety of organisms that make up communities Species richness total number of different species in community Relative abundance proportion of each species represents total population in community 0 Stability 0 Community with higher diversity 0 More productive and more stable in productivity Better able to withstand and recover from environment stress and invasive species Trophic structure 0 Feeding relationships between organisms in community 0 Food chains link trophic levels from producers to top carnivores 0 Food web branching food chain with complex trophic interactions 0 Species may play a role at more than one trophic level Length of food chains 0 Each food chain in a food web is usually only a few lengths long Energetic hypothesis Suggests length is limited by inef cient energy transfer Dynamic hypothesis Long food chains are less stable than short ones Data supports energetic hypothesis Dominant species 0 Those that are more abundant or have highest biomass o Exerts powerful control over occurrence and distribution of other species 0 Might be most competitive in exploiting resources 0 Might be most successful at avoiding predators Keystone species 0 Exert strong control on a community by their ecological roles or niches Not most abundant in a community Foundation species 0 Ecosystem engineers cause physical changes in environment that affects community structure Community control bottom up 0 Bottom up model community organization proposes an unidirectional in uences from lower to higher tropic levels 0 Presence or absence of mineral nutrients determines community structure including abundance of primary producers Community control topdown 0 Top down model trophic cascade model proposes control comes from trophic level above 0 Predators in uence herbivores Role of disturbance 0 Early ecologists viewed community as if in equilibrium 0 Nonequilibrium model always in disturbance Intermediate disturbance hypothesis 0 Suggests that moderate levels of disturbance can foster great diversity can either high ot low levels of disturbance High levels exclude may slow growing species 0 Low levels allow dominant species to exclude less competitive species Succession o Ecological succession sequence of community and ecosystem changes after a disturbance 0 Primary succession where no soil previously existed 0 Secondary succession area still has soil around 0 Early arriving species and later arriving species may be linked Early arrivals help colonize the land before the later arrivals came about Latitudinal gradients of richness 0 Species richness is especially great in tropics and generally declines along an equatorialpolar gradient Temperate and polar communities have started over repeatable following glaciations The greater age of tropics may account for richness and growing season is longer so biological time is faster Climate likely the primary cause of the latitudinal gradient in biodiversity Area effects 0 Speciesarea curve quanti es the idea that all other factors being equal a larger geographic area has more species lsland equilibrium 0 Species richness on islands depends on island size distance from mainland immigration and extinction Equilibrium model of island biogeology maintains that species richness is overlapping number between immigration and extinction Immigration is lower in islands farther from mainland and extinction is higher in small islands Immigration is higher in close islands to the mainland and extinction is lower is large islands 0 Due to more resources for each animal